Carbon-Encapsulated Nickel Catalysts for Electrochemical Urea Removal in Both Seawater and Freshwater Systems

Abstract

This study synthesized carbon-shell-encapsulated nickel metal particles (Ni@NC) via a high-temperature annealing method, developing a highly efficient catalyst for urea pollutant removal in water bodies using electrolysis technology. By optimizing the proportion of urea as the carbon source, the prepared Ni@NC-5 catalyst exhibited outstanding urea oxidation performance in both freshwater and seawater electrolysis systems—requiring only 1.32 V (vs. RHE) to achieve a urea oxidation current density of 10 mA cm−2 and 1.35 V to reach 100 mA cm−2 under alkaline conditions. Through characterization techniques such as XPS and XRD, the specific adsorption mechanism of carbon-shell-encapsulated cubic/hexagonal-phase nickel for the amino and carboxyl groups in urea molecules was elucidated. This work not only provides an efficient catalyst for urea-containing wastewater treatment via electrolysis technology but also offers a novel strategy for the electrochemical degradation of urea pollutants in freshwater and marine environments.

Keywords: water splitting, Electrocatalysts, Urea, Nickel